Method of detecting a polishing endpoint

Abstract

The application provides a polishing endpoint detection method. During a polishing process, a light intensity signal change curve is continuously collected, all mutation inflection points on the light intensity signal change curve are captured according to time sequence and a set capture mutation inflection point condition. During the continuous polishing process, when any mutation inflection point is captured, the polishing parameters are changed according to the type of the mutation inflection point, the thickness of the film layer currently in contact with the polishing pad and the specific polishing requirement, until the mutation inflection point corresponding to the polishing film layer of the final layer is captured and it is determined that there is no film layer to be polished in the current polishing process, and the polishing process is terminated. The polishing endpoint detection method provided by the application can control the polishing steps of all film layers to be polished in the polishing process, change the polishing parameters of each film layer to be polished in real time, so that the polishing rate and accuracy of different film layers can be considered in the same polishing process, and the insufficient polishing or excessive polishing of the final polishing stop layer is avoided.

Description

Technical Field

[0001] This invention relates to the field of semiconductor polishing technology, and in particular to a method for detecting the polishing endpoint. Background Technology

[0002] As products iterate and upgrade, the requirements for the thickness of the film removed by grinding and the thickness of the grinding stop layer are becoming increasingly stringent. CMP cannot afford to under-grind, resulting in residual film, nor can it over-grind, resulting in an excessively thin stop layer. Therefore, in addition to balancing efficiency and cost, product manufacturing also needs to improve the precise control of the thin film transition interface.

[0003] However, current grinding endpoint detection systems / methods are only applicable to controlling a single (film layer) grinding step in the grinding process. Other film layer grinding steps within the same grinding platform process can only be completed at fixed times, making it difficult to balance the grinding rate and accuracy of different film layers. Therefore, current grinding endpoint detection methods are only suitable for processes involving simple material removal and where the thickness of the grinding stop layer or the requirements for grinding dishing are not high. Summary of the Invention

[0004] The purpose of this invention is to provide a grinding endpoint detection method to solve the problem that traditional grinding endpoint detection methods can only control a single (film layer) grinding step in the grinding process. The other film layer grinding steps in the same grinding platform process can only be completed at a fixed time. Traditional grinding endpoint detection methods have difficulty taking into account the grinding rate and accuracy of different film layers.

[0005] To solve the above technical problems, the present invention provides a method for detecting the grinding endpoint, comprising:

[0006] A semiconductor structure is provided, the semiconductor structure comprising at least three stacked film layers of different materials, wherein at least one film layer has a trench structure formed therein;

[0007] A chemical mechanical polishing process is performed on the semiconductor structure from the top film layer to the bottom film layer. During the chemical mechanical polishing process, the reflected light intensity signal is continuously collected to obtain the light intensity signal change curve over time.

[0008] In chronological order, all different types of abrupt change inflection points on the light intensity signal change curve are captured sequentially, wherein each abrupt change inflection point appears at the interface between two film layers of different materials.

[0009] When any of the aforementioned abrupt change inflection points is detected, it is determined whether there are still film layers to be polished in the semiconductor structure. If there are still film layers to be polished in the semiconductor structure, the polishing parameters are changed accordingly based on the type of the abrupt change inflection point and the material and thickness of the film layer currently in contact with the polishing pad. If there are no film layers to be polished in the semiconductor structure, the polishing process is terminated.

[0010] Optionally, in the grinding endpoint detection method, based on the trend of the light intensity signal change curve, the types of abrupt change inflection points include: steep drop type, steep rise type, step jump type, gradual change type, and pulse spike type.

[0011] Optionally, in the grinding endpoint detection method, the trench structure is a shallow trench isolation structure or a metal interconnect structure.

[0012] Optionally, in the grinding endpoint detection method, the semiconductor structure includes:

[0013] A substrate in which a trench is formed;

[0014] A first buffer metal layer covers the substrate and the sidewalls and bottom wall of the trench;

[0015] A second buffer metal layer, wherein the second buffer metal layer covers the first buffer metal layer;

[0016] A main metal layer covers the second buffer metal layer and fills the remaining space of the trench, wherein the first buffer metal layer, the second buffer metal layer and the main metal layer in the trench constitute a metal interconnect structure.

[0017] Optionally, in the grinding endpoint detection method, the substrate includes at least a silicon oxide layer; the first buffer metal layer is made of titanium; the second buffer metal layer is made of titanium nitride; and the main metal layer is made of tungsten.

[0018] Optionally, in the grinding endpoint detection method, the grinding endpoint detection method includes:

[0019] A chemical mechanical polishing process is performed on the semiconductor structure to polish the main metal layer, the second buffer metal layer, and the first buffer metal layer, and the polishing is stopped on the substrate surface. During the chemical mechanical polishing process, the reflected light intensity signal is continuously collected to obtain the light intensity signal change curve of the reflected light intensity signal over time.

[0020] When the first abrupt inflection point on the light intensity signal change curve is captured and the type of the first abrupt inflection point is identified as a steep drop, it is determined that there are still the second buffer metal layer and the first buffer metal layer in the semiconductor structure to be polished. Thus, it is determined that the film layer currently in contact with the polishing pad is the second buffer metal layer, and the polishing parameters for the main metal layer are changed accordingly to the polishing parameters for the second buffer metal layer.

[0021] When the second abrupt inflection point on the light intensity signal change curve is captured and the type of the second abrupt inflection point is identified as steep rise, it is determined that there is still the first buffer metal layer in the semiconductor structure to be polished. Thus, the film layer currently in contact with the polishing pad is determined to be the first buffer metal layer, and the polishing parameters for the second buffer metal layer are changed accordingly to the polishing parameters for the first buffer metal layer.

[0022] If the third abrupt change inflection point on the light intensity signal change curve is identified as a steep drop, it is determined that there is no film layer to be polished in the semiconductor structure, and the polishing process is terminated.

[0023] Optionally, in the grinding endpoint detection method, in the later stage of grinding each film layer, the window of change of the reflected light intensity signal curve is increased by adjusting the grinding pad rotation speed, the grinding pressure in the center region of the wafer and the grinding pressure in the edge region of the wafer, so as to facilitate the capture of the abrupt inflection point on the light intensity signal change curve.

[0024] Optionally, in the grinding endpoint detection method, the grinding endpoint detection method further includes:

[0025] If there are no more films to be polished in the semiconductor structure, then it is determined whether the previous film layer that was removed by polishing needs to undergo a polishing process.

[0026] If the previous layer of film removed by grinding requires a grinding process, then grind away a portion of the current layer that is in contact with the grinding pad; if the previous layer of film removed by grinding does not require a grinding process, then terminate the grinding procedure.

[0027] Optionally, in the grinding endpoint detection method, when any of the abrupt change inflection points is detected, it is determined whether there are still films to be ground in the semiconductor structure. If there are still films to be ground in the semiconductor structure, the grinding parameters are changed according to the type of the abrupt change inflection point and the material of the film currently in contact with the grinding pad. The grinding parameters include at least: grinding pad rotation speed, grinding head rotation speed, grinding pressure in the center region of the wafer, grinding pressure in the edge region of the wafer, grinding time, and grinding fluid flow rate.

[0028] Optionally, in the grinding endpoint detection method, the light intensity signal change curve is filtered, and the filtering conditions of the interval segments of the light intensity signal change curves corresponding to all the films to be ground are kept consistent, so as to ensure the continuity and smoothness of the light intensity signal change curves.

[0029] In summary, this invention provides a method for detecting the end point of grinding. It continuously acquires light intensity signal change curves and, according to time sequence and pre-defined conditions for capturing abrupt change inflection points, captures all different types of abrupt change inflection points on the light intensity signal change curves. During continuous grinding, when any abrupt change inflection point is captured, the grinding parameters are adjusted according to the type of the inflection point, the thickness of the film layer currently in contact with the grinding pad, and its specific grinding requirements, until an abrupt change inflection point corresponding to the final grinding layer is captured and it is determined that there are no other film layers to be ground in this round of grinding, at which point the grinding process is terminated. The grinding end point detection method provided by this application can control the grinding steps of all film layers to be ground in the grinding process, and change the grinding parameters of each film layer to be ground in real time. This allows for the consideration of grinding rate and accuracy of different film layers in the same grinding process, and also avoids insufficient or excessive grinding of the final grinding stop layer, improving the reliability and accuracy of the grinding process. Attached Figure Description

[0030] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention.

[0031] Figure 1 This is a flowchart of the grinding endpoint detection method according to an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the semiconductor structure according to an embodiment of the present invention;

[0033] The reference numerals in the attached figures are explained as follows:

[0034] 10 - Substrate, 21 - First buffer metal layer, 22 - Second buffer metal layer, 30 - Main metal layer. Detailed Implementation

[0035] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clearly illustrate the objectives of the embodiments of the present invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and sometimes use different scales. It should also be understood that, unless specifically stated or indicated, the terms "first," "second," "third," etc., in the specification are only used to distinguish the various components, elements, steps, etc., in the specification, and are not used to indicate the logical or sequential relationships between the various components, elements, steps, etc.

[0036] This invention provides a method for detecting the grinding endpoint, with reference to... Figure 1 , Figure 1 This is a flowchart of a grinding endpoint detection method according to an embodiment of the present invention, the grinding endpoint detection method comprising:

[0037] Step S1: Provide a semiconductor structure, the semiconductor structure comprising at least three stacked film layers of different materials, wherein at least one film layer has a trench structure formed therein; preferably, the trench structure in the at least one film layer is a shallow trench isolation structure or a metal interconnect structure;

[0038] Step S2: Perform a chemical mechanical polishing process on the semiconductor structure from the top film layer to the bottom film layer. During the chemical mechanical polishing process, the reflected light intensity signal is continuously collected to obtain the light intensity signal change curve over time.

[0039] Step S3: Sequentially capture all different types of abrupt change inflection points on the light intensity signal change curve in chronological order, wherein each abrupt change inflection point appears at the interface between two film layers of different materials.

[0040] Step S4: When any of the aforementioned abrupt change inflection points is detected, determine whether there are still film layers to be polished in the semiconductor structure. If there are still film layers to be polished in the semiconductor structure, then change the polishing parameters accordingly based on the type of the abrupt change inflection point and the material and thickness of the film layer currently in contact with the polishing pad. If there are no film layers to be polished in the semiconductor structure, then terminate the polishing process.

[0041] The grinding parameters include at least: grinding pad rotation speed, grinding head rotation speed, grinding pressure in the center region of the wafer, grinding pressure in the edge region of the wafer, grinding time, and grinding fluid flow rate.

[0042] Preferably, since the intensity of light reflected by film layers of different materials varies significantly, the types of abrupt change inflection points, based on the trend of the light intensity signal change curve, include: steep drop type, steep rise type, step jump type, inflection point gradual change type, and pulse peak type.

[0043] In this embodiment, specifically, (1) the sudden inflection point of the steep drop type is manifested as the moment when the curve goes from being stable and flat to a sudden and sharp drop;

[0044] (2) The sudden inflection point of a steep rise is characterized by the moment when the curve is stable and then suddenly rises rapidly;

[0045] (3) The abrupt change in the step jump transformation is the instant when the curve is stable → straight and jumps to another stable interval. There is no steep slope on either side of the abrupt change in the step jump transformation.

[0046] (4) The sudden inflection point of the gradual change type is characterized by a smooth curve → the appearance of a significant bending inflection point → then a slow rise or fall. The moment when a significant bending inflection point appears in this section of the curve.

[0047] (5) The sudden inflection point of the pulse peak type is characterized by the curve being stable → a momentary peak appears and then returns to stability. The momentary peak appears in the curve.

[0048] In other embodiments, if there are no other films to be polished in the semiconductor structure, step S4 may not directly terminate the polishing process, but may further include:

[0049] If there are no more films to be polished in the semiconductor structure, then it is determined whether the previous film layer that was removed by polishing needs to undergo a polishing process.

[0050] If the previous layer of film removed by grinding requires a grinding process, then grind away a portion of the current layer that is in contact with the grinding pad; if the previous layer of film removed by grinding does not require a grinding process, then terminate the grinding procedure.

[0051] This application takes the metal interconnect structure in a polished semiconductor structure as an example, referring to... Figure 2 , Figure 2 This is a schematic diagram of a semiconductor structure according to an embodiment of the present invention. The semiconductor structure includes:

[0052] A substrate 10, wherein a groove is formed in the substrate 10;

[0053] A first buffer metal layer 21 covers the substrate 10 and the sidewalls and bottom wall of the trench;

[0054] The second buffer metal layer 22 covers the first buffer metal layer 21;

[0055] A main metal layer 30 covers the second buffer metal layer 22 and fills the remaining space of the trench, wherein the first buffer metal layer 21, the second buffer metal layer 22 and the main metal layer 30 in the trench constitute a metal interconnect structure.

[0056] In this embodiment, the substrate 10 includes at least a silicon oxide layer, and the substrate 10 may also include a silicon substrate, wherein the silicon oxide layer is located on the silicon substrate; the first buffer metal layer 21 is made of titanium; the second buffer metal layer 22 is made of titanium nitride; and the main metal layer 30 is made of tungsten.

[0057] Specifically, with Figure 2 The semiconductor structure shown is the object to be polished, and the polishing endpoint detection method includes:

[0058] Step S10: Perform a chemical mechanical polishing process on the semiconductor structure to polish the main metal layer 30, the second buffer metal layer 22, and the first buffer metal layer 21 and stop on the surface of the substrate 10. During the chemical mechanical polishing process, the reflected light intensity signal is continuously collected to obtain the light intensity signal change curve of the reflected light intensity signal over time.

[0059] Specifically, the polishing pad has an optical window. During the polishing process, the semiconductor structure (wafer) is pressed onto the polishing pad by the polishing head, with the polished surface of the wafer facing down and directly facing the optical window. During the polishing process, the wafer and the polishing pad rotate together. A monochromatic laser or white light is emitted from below the polishing pad, passing through the optical window and vertically illuminating the rotating wafer. The polished surface of the wafer is a mirror-level highly reflective surface, so the light undergoes mirror reflection and is directed vertically downward (returning along the original path). The optical sensor inside the polishing machine can collect the intensity signal of the reflected light in real time.

[0060] Preferably, the light intensity signal variation curve is filtered, and the filtering conditions of the interval segments of the light intensity signal variation curves corresponding to all the films to be ground are kept consistent, so as to ensure the continuity and smoothness of the light intensity signal variation curves.

[0061] Preferably, in the later stages of polishing each film layer, the polishing pad speed, polishing pressure in the center region of the wafer, and polishing pressure in the edge region of the wafer are adjusted to increase the window for changes in the reflected light intensity signal curve, so as to facilitate the capture of abrupt inflection points on the light intensity signal change curve.

[0062] Step S20: When the first abrupt change inflection point on the light intensity signal change curve is captured and the type of the first abrupt change inflection point is identified as a steep drop, it is determined that there are still the second buffer metal layer and the first buffer metal layer in the semiconductor structure to be polished, thereby determining that the film layer currently in contact with the polishing pad is the second buffer metal layer, and the polishing parameters for the main metal layer are changed accordingly to the polishing parameters for the second buffer metal layer.

[0063] In this embodiment, during the later stages of polishing the main metal layer (tungsten layer) 30, the polishing pad rotation speed is reduced and the polishing pressure in the center region and edge region of the wafer is increased to enlarge the window for the change of the reflected light intensity signal curve, so as to facilitate the capture of the abrupt inflection point on the light intensity signal change curve.

[0064] When the main metal layer (tungsten layer) 30 on the surface of the second buffer metal layer 22 around the groove is worn through and comes into contact with the second buffer metal layer (titanium nitride layer) 22, the refractive index / reflectivity of the two metals is significantly different. The light reflectivity of the titanium nitride layer is much lower than that of the tungsten layer, and the reflected light intensity signal drops sharply in an instant, forming a steep drop (sudden decrease) change curve. The grinding endpoint detection method provided in this application can capture the steep drop inflection point, thereby accurately identifying that the film layer currently in contact with the grinding pad has transitioned from the main metal layer 30 to the second buffer metal layer 22.

[0065] Step S30: When the second abrupt change inflection point on the light intensity signal change curve is identified as a steep rise, it is determined that there is still a first buffer metal layer to be polished in the semiconductor structure. Thus, the film layer currently in contact with the polishing pad is determined to be the first buffer metal layer, and the polishing parameters for the second buffer metal layer are changed accordingly to the polishing parameters for the first buffer metal layer.

[0066] During the grinding stage of the second buffer metal layer (titanium nitride layer) 22, the light intensity signal value is relatively stable. When the second buffer metal layer (titanium nitride layer) 22 is ground through and comes into contact with the first buffer metal layer (titanium layer) 21, due to the large difference in refractive index / reflectivity between the two metals, the light reflectivity of the titanium layer is much higher than that of the titanium nitride layer. Therefore, when the second buffer metal layer (titanium nitride layer) 22 is ground through and comes into contact with the first buffer metal layer (titanium layer) 21, the reflected light intensity signal increases rapidly and instantaneously, forming a steep (suddenly rising) change curve.

[0067] In this embodiment, during the later stages of polishing the second buffer metal layer (titanium nitride layer) 22, the window for the change in the reflected light intensity signal curve can be increased by reducing the polishing pad rotation speed and increasing the polishing pressure in the wafer center region and wafer edge region. This facilitates the capture of steeply rising abrupt inflection points on the light intensity signal change curve. The polishing endpoint detection method provided in this application can accurately capture steeply rising abrupt inflection points, thereby accurately identifying that the film layer currently in contact with the polishing pad has transitioned from the second buffer metal layer to the first buffer metal layer.

[0068] Step S40: Continue capturing the third abrupt change inflection point on the light intensity signal change curve. When the type of the third abrupt change inflection point is identified as a steep drop, and it is determined that there is no film layer to be polished in the semiconductor structure, the polishing process is terminated.

[0069] During the grinding stage of the first buffer metal layer (titanium layer) 21, the reflected light intensity signal is stable. When the first buffer metal layer (titanium layer) 21 is ground through and comes into contact with the substrate (silicon dioxide) 10, the difference in refractive index and the rate of change of reflected light intensity between the metal material and the insulating medium is extremely large. Furthermore, the interface between the first buffer metal layer (titanium layer) 21 and the substrate (silicon dioxide) 10 will be accompanied by thin film interference oscillation. Therefore, the change in the light intensity signal change curve is as follows: from a stable high value → periodic oscillation → gradually decreasing to a stable low value. The change amplitude of the reflected light intensity signal is very obvious, belonging to a steeply decreasing curve with oscillation characteristics. Thus, a steeply decreasing abrupt inflection point appears on the light intensity signal change curve.

[0070] In this embodiment, during the later stages of polishing the first buffer metal layer (titanium layer) 21, the polishing pad rotation speed is reduced and the polishing pressure in the center region and edge region of the wafer is increased to enlarge the window of the reflected light intensity signal curve change, so as to facilitate the capture of the steep drop inflection point with oscillation characteristics on the light intensity signal change curve.

[0071] In other embodiments, if it is determined that there is no film layer to be polished in the semiconductor structure, step S40 may not directly terminate the polishing process, but may further include:

[0072] If there are no more films to be polished in the semiconductor structure, it is determined whether the first buffer metal layer (titanium layer) 21 that has been polished away needs to undergo a polishing process.

[0073] If the first buffer metal layer (titanium layer) 21 needs to undergo a polishing process, then a portion of the thickness of the substrate 10 is removed by polishing; if the first buffer metal layer (titanium layer) 21 does not need to undergo a polishing process, then the polishing process is terminated.

[0074] In this application, during the later stages of polishing each film layer, the window for the change of the reflected light intensity signal curve can be increased by adjusting polishing parameters such as the polishing pad rotation speed, the polishing pressure in the wafer center area, and the polishing pressure in the wafer edge area. This allows for the precise capture of abrupt inflection points on the light intensity signal change curve. Based on different abrupt inflection points, the polishing steps of different films to be polished in the polishing process can be controlled. Furthermore, based on the type of each abrupt inflection point, the thickness of the film layer in contact with the polishing pad each time, and its specific polishing requirements, the polishing parameters of each film layer to be polished can be changed in real time. This allows for the consideration of polishing rates and precision of different films in the same polishing process, and also avoids insufficient or excessive polishing of the final polishing stop layer, thereby improving the reliability and precision of the polishing process.

[0075] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for detecting the grinding endpoint, characterized in that, include: A semiconductor structure is provided, the semiconductor structure comprising at least three stacked film layers of different materials, wherein at least one film layer has a trench structure formed therein; A chemical mechanical polishing process is performed on the semiconductor structure from the top film layer to the bottom film layer. During the chemical mechanical polishing process, the reflected light intensity signal is continuously collected to obtain the light intensity signal change curve over time. In chronological order, all different types of abrupt change inflection points on the light intensity signal change curve are captured sequentially, wherein each abrupt change inflection point appears at the interface between two film layers of different materials. When any of the aforementioned abrupt change inflection points is detected, it is determined whether there are still film layers to be polished in the semiconductor structure. If there are still film layers to be polished in the semiconductor structure, the polishing parameters are changed accordingly based on the type of the abrupt change inflection point and the material and thickness of the film layer currently in contact with the polishing pad. If there are no film layers to be polished in the semiconductor structure, the polishing process is terminated.

2. The grinding endpoint detection method according to claim 1, characterized in that, Based on the trend of the light intensity signal change curve, the types of abrupt change inflection points include: steep drop type, steep rise type, step jump type, gradual change type, and pulse spike type.

3. The grinding endpoint detection method according to claim 1, characterized in that, The trench structure is a shallow trench isolation structure or a metal interconnect structure.

4. The grinding endpoint detection method according to claim 2, characterized in that, The semiconductor structure includes: A substrate in which a trench is formed; A first buffer metal layer covers the substrate and the sidewalls and bottom wall of the trench; A second buffer metal layer, wherein the second buffer metal layer covers the first buffer metal layer; A main metal layer covers the second buffer metal layer and fills the remaining space of the trench, wherein the first buffer metal layer, the second buffer metal layer and the main metal layer in the trench constitute a metal interconnect structure.

5. The grinding endpoint detection method according to claim 4, characterized in that, The substrate includes at least a silicon oxide layer; the first buffer metal layer is made of titanium; the second buffer metal layer is made of titanium nitride; and the main metal layer is made of tungsten.

6. The grinding endpoint detection method according to claim 5, characterized in that, The grinding endpoint detection method includes: A chemical mechanical polishing process is performed on the semiconductor structure to polish the main metal layer, the second buffer metal layer, and the first buffer metal layer, and the polishing is stopped on the substrate surface. During the chemical mechanical polishing process, the reflected light intensity signal is continuously collected to obtain the light intensity signal change curve of the reflected light intensity signal over time. When the first abrupt inflection point on the light intensity signal change curve is captured and the type of the first abrupt inflection point is identified as a steep drop, it is determined that there are still the second buffer metal layer and the first buffer metal layer in the semiconductor structure to be polished. Thus, it is determined that the film layer currently in contact with the polishing pad is the second buffer metal layer, and the polishing parameters for the main metal layer are changed accordingly to the polishing parameters for the second buffer metal layer. When the second abrupt inflection point on the light intensity signal change curve is captured and the type of the second abrupt inflection point is identified as steep rise, it is determined that there is still the first buffer metal layer in the semiconductor structure to be polished. Thus, the film layer currently in contact with the polishing pad is determined to be the first buffer metal layer, and the polishing parameters for the second buffer metal layer are changed accordingly to the polishing parameters for the first buffer metal layer. If the third abrupt change inflection point on the light intensity signal change curve is identified as a steep drop, it is determined that there is no film layer to be polished in the semiconductor structure, and the polishing process is terminated.

7. The grinding endpoint detection method according to claim 1, characterized in that, In the later stages of polishing each film layer, the polishing pad speed, polishing pressure in the center region of the wafer, and polishing pressure in the edge region of the wafer are adjusted to increase the window for changes in the reflected light intensity signal curve, so as to facilitate the capture of abrupt inflection points on the light intensity signal change curve.

8. The grinding endpoint detection method according to claim 1 or 6, characterized in that, The grinding endpoint detection method further includes: If there are no more films to be polished in the semiconductor structure, then it is determined whether the previous film layer that was removed by polishing needs to undergo a polishing process. If the previous layer of film removed by grinding requires a grinding process, then grind away a portion of the current layer that is in contact with the grinding pad; if the previous layer of film removed by grinding does not require a grinding process, then terminate the grinding procedure.

9. The grinding endpoint detection method according to claim 1, characterized in that, When any of the aforementioned abrupt change inflection points is detected, it is determined whether there are still films to be polished in the semiconductor structure. If there are still films to be polished in the semiconductor structure, the polishing parameters are changed accordingly based on the type of the abrupt change inflection point and the material of the film currently in contact with the polishing pad. The polishing parameters include at least: polishing pad rotation speed, polishing head rotation speed, polishing pressure in the center region of the wafer, polishing pressure in the edge region of the wafer, polishing time, and polishing fluid flow rate.

10. The grinding endpoint detection method according to any one of claims 1-9, characterized in that, The light intensity signal variation curve is filtered, and the filtering conditions for the interval segments of the light intensity signal variation curves corresponding to all the films to be ground are kept consistent to ensure the continuity and smoothness of the light intensity signal variation curves.

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